looks like the distributor is giving you too much mechanical advance. what type of distributor are you using?
It's MSD Pro Billet...i just finished with it & i got it where i believe it needs to be. honestly i never would have thought i'd have this many hours and nasty words about timing issues. at one point i had 55* total..blew my mind. right now im at 18 inital and 35 total..best i could get and im happy with it right now. heading out of town to race in the morning..tech inspection around 11am..might even get some passes at night (we dont usually) but they need more rubber laid down.
I guess just don't understand your reasoning....... If you have to use it you've already lost the race??? I'm guessing your under the assumption that all nitrous is activated via a button??? Using nitrous is just like using a turbo or a supercharger......or do using them mean you've already lost the race as well? No matter where its coming from its all the same......more particles of oxygen per volume means more fuel which makes more power. There's no more risk running nitrous then there is a turbo or a supercharger unless your just totally against much cooler intake temps and more power. Nitrous has come a long way if you haven't looked at the market within the last 10 years...... all sorts of safties and cool stuff running around like fuel pressure shut off solenoids....window switches.....etc etc etc.
Got your PM. Super busy lately and sorry for the late reply. First off.. 45 is WAAAYYYY too much timing for spray. Especially with this heads efficient combustion chamber design. Of course every combo is going to be different.. but pulling 3-4 degrees out per every 100 shot is a good ballpark to help prevent making "bad tune" souvenir ashtrays. It's usually more financially prudent.. read as "cheaper, easier, and much safer".. to take some extra lead out(say 8 degrees to give 30 total) and just add it back in as needed to sneak up on plug colors and ET rather than living on the ragged edge right off the starting line. In the scheme of things plugs are pretty cheap, so bring a few fresh sets to help add reading clarity during initial tuning stages and put the old ones back in after the races. Many guys I know use dedicated race sets that never see street duty or simply just use fresh plugs during race prep. Also keep in mind that using better fuel will give you a notably larger window of margin for tuning errors too. Seems pricey during initial sticker shock.. and surely just depends on how much you value your motor.. but dedicated race fuel is very cheap insurance during a weekend of "drag spraycing". IMO, 18 is a good number to shoot for and you just need to use a vacuum gauge to gain the most idle and light cruise vacuum readings that you can possibly reach with your tuning. As you seem to have already discovered.. most newer tuners quickly find that what's good for the goose may not necessarily be good for the gander and adding initial lead means using more limiter (bushings in your case) for reducing the total lead. Just keep in mind that heavier initial and quicker sweeps are for idle and part throttle tuning gains and don't necessarily do much for ET's in themselves if you leave at an RPM where the timing has all come in anyways. It(greater engine vacuum) can however improve throttle response which allows you to come up on the brake and/or converter more consistently which can and does help the number on occasion. Generally speaking.. the bigger the cam(specifically in relation to the CID).. the more initial lead and aggressive centrifugal sweep you'll need to compensate for the added shortcomings that come with it. This is because the extra overlap created by more duration(particularly on the intake side) and using a tighter LCA will cause even greater low speed mixture dilution and reduces mixture homogenization which makes for even lazier/incomplete combustion dynamics than is typical during low piston/intake runner speed. Hope that helps and I didn't arrive too late to the party to prevent any souvenirs from being made. PS. I dug up the link for the bushings I use on some of my junk. That page also goes into some of the same detail I did in the above. I do not agree with the "no need to have the timing come in before the converter flashes" though. It's been my experience that such advice would only pertain to a full race duty setup.. not a street/strip motor. The fact is that a converter still comes in well before the full flash speed and added timing still helps. http://www.4secondsflat.com/MSD Distributor Tuning.htm PS.PS. If you're serious about timing?.. get one of these boxes. Money well spent. http://www.msdignition.com/Products/Ignitions/6530_-_MSD_Digital_Programmable_6AL-2.aspx
Or do like I did and just get rid of the distributor and punch in any timing you want with your computer. Also can hold two different timing programs, one for normal driving and the other for when you spray. http://www.autosportlabs.com/product/megajolte/
Was not too late, i worked on the car many many many hours untill friday morning i left for the races, then worked on it for about 2 hours after tech, i have 4 different sets of plugs for it...money isn't the issue when it comes to "saving" my motor. i got it dialed in to 17 inital and 32 all in. it was a bit sluggish so i changed plugs and sprayed it a bit..ran 11.50's (im not caged so it's actually as fast as i could go anyways) so i kept with that and i raced, raced, and raced some more..actually finished 2nd out of a 70 car class. cheque is in the mail i would have also won due to the car running the exact same times each go at it, except for my slicks were spinning on the rims! time for beadlocks...anyways i'll be looking into this timing more this weekend to get it worked out better. i feel my car easily has 10-second passes in it once its caged and tuned better.
Nice consistency there. FWIW.. with that cam and converter/gear combo.. I'd lay down good money that your car will surely ET better with a Vic JR or comparable. The RPM's a good manifold for the street.. but in un-ported form.. it starts falling short(especially on a 347) where that motor really wants to run all the way to the stripe. A 25-30 horse bolt on awaits you.
Glad to see you have got things sorted out. It really sucks not being able to run car to full potential due to lack of roll bar but rule is there for your protection, been there done that
yep. ill send it in for a cage this winter..i just need to figure out the best way to have the cage built to fit my car and not hack up my brand new interior.. was just looking at victor jr intake's as well for like 289$$ on summit..guy called me earlier i met at the races. has a spare one for sale 150$
Decent price. Like I said in the above.. RPM's a great intake for street duty.. especially for heavier cars and/or pulling less converter and gear.. but you have none of those shortcomings with your combo. Although shift recovery rpm may suffer a tad bit.. your combo surely flashes right past a dual planes sweet spot anyways. But don't worry.. more spray fixes that every time.
